The present invention relates to an illumination system, and particularly relates to a color/general illumination system suitable for illuminating a relatively wide range of area as in cove-lighting.
In hotels and restaurants, a so-called indirect lighting that illuminates the space by the light reflected from the wall, ceiling or floor is widely adopted. One way of such indirect lighting is known as xe2x80x9ccove-lightingxe2x80x9d in which, typically, a horizontally extending trough called a xe2x80x9ccovexe2x80x9d is provided to a portion of a wall surface near the ceiling and an illumination device is concealedly placed in the cove to emit light to the ceiling. An illumination system for such cove-lighting usually comprises a plurality of illumination devices disposed along the cove to achieve as uniform illumination as possible along the entire length of the cove.
In such conventional illumination systems using a plurality of illumination devices, however, each of the illumination devices was independently connected to the power supply, and thus there was a problem that the cable routing work tended to be complicated and require a long time. Also, in such a case that the space for installing the illumination system was limited (e.g., when the cove width was tightly narrow), a further problem could arise that there was not a sufficient room for cable routing.
Besides, recently, light emitting diodes (LEDs) have been used in wider fields as a light source of an illumination device. Since the LEDs dissipate less heat, they are suitable for a light source of cove-lighting devices which tend to be placed in a relatively narrow space. In a case that LEDs of three primary colors (red, green and blue) are used as light sources, additive mixture of the red, green and blue lights emitted from the LEDs with controlled proportion of the RGB lights can allow the ceiling, wall and the like to be illuminated in desired colors, which would significantly enhance the illumination effect. However, in order to conduct such color illumination, it is necessary to provide the illumination device with a control unit (such as a CPU) for controlling the LEDs of one color independently from the LEDs of the other colors, resulting in a higher manufacturing cost of the illumination device. This problem can be conspicuous particularly in such an illumination system that utilizes a plurality of illumination devices to illuminate light in relatively wide areas as in the cove-lighting.
In view of such problems of the prior art, a primary object of the present invention is to provide an illumination system that can significantly reduce the effort and time required for cable routing.
A second object of the present invention is to provide an illumination system that can illuminate relatively wide areas with a minimized cost increase.
A third object of the present invention is to provide an illumination system that is suitable for use in a relatively limited installation space.
A fourth object of the present invention is to provide an illumination system that can allow easy cable routing and provide a greater freedom of arrangement.
A fifth object of the present invention is to provide a color illumination system that can conduct color illumination in relatively wide areas without causing a significant cost increase.
A sixth object of the present invention is to provide an illumination device that requires a small installation space and is easy to handle.
According to the present invention, such objects can be accomplished by providing an illumination system, comprising: a first illumination unit comprising a pair of power supply contacts for connection to a commercial AC power source, a light source connected between the pair of power supply contacts, a control circuit connected in series to the light source to control electric current flowing through the light source, and a first connection cord connected to the light source; and a second illumination unit comprising a light source and a first connection cord connected to the light source, wherein the first connection cord of the first illumination unit and the first connection cord of the second illumination unit are connected to each other so that the light source of the first illumination unit and the light source of the second illumination unit are connected in parallel to each other. In such a configuration, it is possible to supply electric power to the second illumination unit (sub unit) via the first illumination unit (main unit) as well as to control the light source of the second illumination unit by the control circuit of the first illumination unit. Therefore, the second illumination unit does not need its own power cable for direct connection to an outside power source such as the commercial AC power source, and therefore, not only a space required for the cable routing is reduced but also an effort and time for the cable routing can be considerably reduced. Also, since the second illumination unit does not have to comprise a control circuit, the manufacturing cost thereof can be minimized.
Preferably, the second illumination unit further comprises a second connection cord connected to the light source commonly with the first connection cord. By using the second connection cord, the second illumination unit can be further connected to another illumination unit. Also, if each of the illumination units comprises a longitudinal support member for supporting the light source, and each connection cord is provided in a vicinity of an associated longitudinal end of the support member of each illumination unit, connection of longitudinally adjoining illumination units can be made easily. This would make the illumination system particularly suitable for use in linear lighting such as cove-lighting, for example. In general, in accordance with this aspect of the present invention, an arbitrary number of illumination units (sub units) that, like the second illumination unit, do not comprise a control circuit can be joined together to achieve an illumination system of a desired length with minimized increase in the total system cost.
Further preferably, the first illumination unit further comprises a second connection cord connected to the light source commonly (or in parallel) with the first connection cord, the system further comprises a third illumination unit comprising a light source and a first connection cord connected to the light source, and the second connection cord of the first illumination unit is connected to the first connection cord of the third illumination unit so that the light source of the first illumination unit and the light source of the third illumination unit are connected in parallel to each other. In this way, the second and third illumination units can be connected to the first illumination unit in a bifurcated relationship (referred to herein as xe2x80x9cbifurcation connectionxe2x80x9d or xe2x80x9cbifurcation jointxe2x80x9d), which can result in significant increase in the design freedom of system layout.
According to another aspect of the present invention, there is provided an illumination system, comprising: first and second illumination units, each having a light source and first and second connection cords commonly connected to the light source: and a control unit separate from the first and second illumination units, the control unit having a pair of power supply contacts and a control circuit, wherein the first illumination unit is connected to the control unit via its first connection cord so that the light source of the first illumination unit is connected between the pair of power supply contacts of the control unit via the control circuit of the control unit; wherein the second connection cord of the first illumination unit is connected to the first connection cord of the second illumination unit so that the light source of the first illumination unit and the light source of the second illumination unit are connected in parallel to each other; and wherein each of the first and second illumination unit has a longitudinal support member for supporting the light source and each connection cord is provided in a vicinity of an associated end of the support member of each illumination unit. In such a configuration, the light source in each of the illumination units can be controlled by the control unit separate from the illumination units, and therefore each illumination unit does not have to be equipped with its own control circuit. This can lead to a reduced total manufacturing cost of the illumination system. Also, since each illumination unit can be supplied with electric power via adjacent illumination unit connected thereto via the connection cord, there is no need for each illumination unit to have its own power cable for direct connection to an outside power source such as the commercial AC power source. The control unit does not have to be located near the illumination units at the site, and can be installed on an interior wall of a room, for example, so that the control unit can be readily operable by the user.
It will be preferable if each of the first and second illumination units further comprises a light-transmissive tubular member for accommodating the support member and the light source, and a cap member having a bottom wall and a cylindrical side wall and attached to an end of the tubular member, with the bottom wall being formed with a groove or slit for receiving an associated end of the support member. In this way, even when the system is installed in dusty environment, the tubular member and the cap member can advantageously prevent dust from causing damage to the light source or any circuits in the illumination units or facilitate maintenance or cleaning of the illumination units. The groove or slit formed in the cap member to receive the end of the support member allows easy and quick assembly of the illumination unit. If the side wall of the cap member is formed with a hole so as to allow an associated connection cord to be drawn out therethrough, it is possible to place longitudinally adjacent illumination units closely to each other, desirably allowing a xe2x80x9cseamlessxe2x80x9d illumination having substantially no dark areas between the adjacent units. Also, in the case that the light source of each of the first and second illumination units comprises a plurality of light emitting elements, it will be preferable if the longitudinal support member consists of a printed circuit board on which the plurality of light emitting elements are mounted so that the mechanical support and the electric connection of the light emitting elements can be achieved simultaneously.
The illumination system can be preferably implemented as a color illumination system if the light source of each of the first and second illumination units comprises a red light source, a green light source and a blue light source; the control circuit comprises first, second and third control elements connected in series to the red light source, green light source and blue light source, respectively, of the first illumination unit; and the second connection cord of the first illumination unit and the first connection cord of the second illumination unit are connected to each other so that light sources of a same color in these illumination units are connected in parallel to each other. As a modified embodiment, it is also possible that the second connection cord of the first illumination unit and the first connection cord of the second illumination unit are provided with respective connectors which are adapted so that light sources of different colors in the first and second illumination units can be connected in parallel to each other via the connectors. Preferably, the red light source comprises a red LED set having a series-connected plurality of red LEDs, the green light source comprises a green LED set having a series-connected plurality of green LEDs, and the blue light source comprises a blue LED set having a series-connected plurality of blue LEDs, and each of the first, second and third control elements consists of a switching element. By using LEDs and switching elements, the power consumption and heat generation of each illumination unit can be minimized, allowing a number of illumination units to be joined together without causing a problem.
According to yet another aspect of the present invention, there is provided an illumination unit, comprising: a pair of power supply contacts for connection to a commercial AC power source; a light source comprising a plurality of LEDs mounted on one side of a longitudinal printed circuit board, the light source being connected between the pair of power supply contacts; a control circuit attached on the other side of the printed circuit board and connected in series to the light source; a transformer-less AC/DC converter attached on the other side of the printed circuit board and connected to the power supply contacts in order to supply a DC voltage to the control circuit; and a light transmissive tubular member for accommodating the light source, printed circuit board, control circuit and transformer-less AC/DC converter. Since the light source, printed circuit board, control circuit and transformer-less AC/DC converter are all accommodated in the tubular member, an illumination unit that is easy to handle and has a small footprint can be provided. This illumination unit can be directly connected to the commercial AC power source, and thus can serve as an independent, stand-alone illumination device.
According to further aspect of the present invention, there is provided an illumination unit, comprising: a light source, and at least three connection cords commonly connected to the light source so as to enable the illumination unit to make a bifurcation connection with other illumination units. The xe2x80x9cbifurcation connectionxe2x80x9d of illumination units can lead to a greater freedom in layout of the illumination system comprising the illumination units. Such an illumination unit can be implemented as a color illumination unit if the light source comprises a red light source, a green light source and a blue light source, and each of the connection cord is provided with a connector which has a first pin connected to a common line, a second pin connected to the red light source, a third pin connected to the green light source and a fourth pin connected to the blue light source. In the illumination unit for enabling xe2x80x9cbifurcation connectionxe2x80x9d also, in view of facilitating longitudinal arrangement of illumination units, it will be preferable if the unit further comprises a longitudinal support member for supporting the light source, wherein at least one of the connection cords is provided in a vicinity of one end of the support member and at least one of the other connection cords is provided in a vicinity of the other end of the support member.
Other and further objects, features and advantages of the invention will appear more fully from the following description.